FWIW, a portable generator like a Wen 56235i, 2350 surge watts/1900 rated watts, selling for $430 on Amazon, should be able to keep most refrigerators or freezers cold. Surge is the important factor, there's a surge when the refrigerator kicks on and if the generator can't handle the surge it will go into overload and shut down. Doesn't necessarily need to run continuously if the door isn't being opened continuously. Or, get a bit larger portable (more watts, and heavier/less portable), still a modest cost vs throwing out a large amount of food.
If you want to operate more stuff concurrently it gets a little more complicated but can be done. Can get one unit, add another later via a parallel connection that's available from Wen and others, a plug and play configuration, if cost is a consideration.
Don't run it inside, and get a heavy extension cord, at least 12 gauge. Follow operating instructions carefully.